Conversion of hydrocarbon oils



Patented Sept. 3, i194? CONVERSION OF HYDROCARBON OILS Jacob E. Ahlbergand Charles L. Thomas, Riverside, Ill., assignors to Universal OilProducts Company, Chicago, Ill., a corporation of Delaware No Drawing.Application October 7, 1944,

Serial No. 557,719

3 Claims. (Cl. 196-52) This application is a continuation-in-part ofSerial Number 373,308, filed January 6, 1941, now Patent Number2,369,001, which was a continuation-in-part of our earlier applicationsSerial Number 132,092, filed March 20, 1937, now Patent Number2,282,922, and Serial Number 176,648, filed November 26, 1937, nowPatent Number 2,229,353.

This invention relates to the conversion of hydrocarbons such aspetroleum fractions and hydrocarbonaceous oils generally includingsynthetic oils from various carbon containing sources. Morespecifically, the invention is concerned with a modification ofhydrocarbon oil conversion processes in the presence of catalyticmaterials which promote the formation of very high antiknock gasoline.The catalysts peculiar to this invention are prepared according todefinite procedures so that they are highly selective when in prolongeduse but are less disposed to accumulate carbonaceous deposits than cat-'alysts heretofore used for this purpose.

The art of pyrolytically cracking gasoline to produce relatively highantiknock gasoline is well established and it is now generally knownthat gasolines of still higher antiknock value may be obtained whencracking under non-pyrolytic conditions in the presence of various typesof catalysts. It has long been known that cracking catalysts of thealuminum chloride type give high antiknock gasoline but cannot beemployed without serious difficulties due to the deposition ofcarbonaceous material on the catalyst and the regeneration of thealuminum chloride catalyst. It is also known that when employingcatalysts of the reduced metal types such as iron or nickel for examplethat hydrocarbon reactions are accelerated which lead largely to theformation of gas rather than to the formation of predominant yields ofhigh antiknock gasoline. With this type of catalyst a very high rate ofcarbon deposition is experienced. The catalysts of the present inventionare synthetic and depend upon mixing hydrated silica and certainhydrated metal oxides for their high activity. These catalysts may ingeneral be employed under conditions where carbon formation on thecatalyst can be handled in a practical manner. It is the main object ofthe present invention to provide a process wherein the latter type ofcatalysts are employed in a modified form whereby carbon and gas formingreactions are substantially reduced. The catalysts are of a refractorycharacter which enables them to retain their catalytic properties overextended periods of time under high tem- 2 perature conditions of useand regeneration, and they are also characterized by definite methods ofmanufacture and exact reproducibility.

In one specific embodiment the present invention consists of a processfor the conversion of hydrocarbon oil which comprises subjecting the oilunder conversion conditions to contact with a catalyst compositecomprising precipitated hydrated silica, precipitated hydrated alumina,and precipitated hydrated zirconia substantially free of alkali metalcompounds and a relatively inactive non-adsorptive natural occurringsilica substantially free of alkali and alkaline earth metal compoundsand of metal oxide impurities.

According to the present invention hydrocarbon fractions such as highboiling petroleum distillates are cracked at a temperature within theapproximate range of 700 to 1150 F. under a pressure of substantiallyatmospheric to approximately 1000 pounds per square inch while incontact with modified synthetic catalysts such as modified composites ofhydrated alumina deposited upon hydrated silica. Although this is apreferred active catalyst material, similar silica-zirconia or.silica-alumina-zirconia composites may be used. .Also composites ofhydrated silica with hydrated magnesia, hydrated thoria, hydratedvanadla, and other hydrated metal oxides may be used since they havehydrocarbon-splitting properties but are not equivalent among themselvesor to the silica-alumina and silica-zirconia composites in theircatalytic effectiveness. The catalysts are preferably prepared asmixtures of the hydrated oxide gels and are mixed with a relativelyinactive heat resistant material such as kaolin substantially free fromiron oxide and other metal oxide impurities. vAlthough the relativelyinactive material may be mixed with the gel materials during theirpreparation it has been found that the gel material is preferably addedimmediately before drying to produce a powdered catalyst, immediatelybefore forming the mass into particles such as in is thoughtoiasacatalyst. Thesematerialsin our experience have practically nocatalytic activity in cracking reactions as compared to the highlyactive synthetic catalytic materials subsequently described. Some smalldegree of cracking may occur in the presence of such siliceous materialsbut the cracked motor fuel product resulting from the treatmentresembles much more closely the product from thermal cracking which islower in anti-knock value and has a different hydrocarbon character thanthe catalytically cracked product obtained when the catalysts of thepresent invention are employed. Among the above silica materials isdiatomaceous earth which as ordinarily obtained has only arestricted'use in the present invention since if large amounts areadded, the final catalyst particles obtained therefrom do not havesuitable density and are less desirable in the hydrocarbon conversionreactions.

Similarly, as the above inactive materials, various other well-knownsilica materials have practically no catalytic activity. These maybeidentified by their mineralogical. optical or X-ra nature and includehydrated natural silicas such as opal, chalcedony and tripoli, andanhydrous silicas such as vitreous or amorphous silica, the a andp-quartzes, the a, B1 and flz-tridymites and the a and fi-crystobalites.In contrast to these silica materials are hydrated silica gel, silicahydrogel or precipitated hydrated silica which are not used as are theabove relatively inactive materials. These latter hydrated silicas havea certain degree of catalytic activity which how'- ever does notapproach the: high activities of the composited active catalyticmaterialemployed in the present invention and the octane numbers 01' the motorfuel resulting from contact with these silica gel materials are muchlower.

Similarly as for the inactive silicas, many hydrated and anhydrous formsof inactive alumina are known such as bayerite, a-alumina trihydrate andgibbsite, 'y-alllmlna trihydrate; di-

aspore, a-alumina monohydrate and boehmite which is 'y-alllminamonohydrate; corundum a-alumina and fi-alumina. If these materials aremixed with the relatively inactive silica,materials above described,there is no improvement in the catalytic properties. Some bauxites, i.e., alumina dihydrates and particularly 'y-alumina which is known asactivated alumina, have varying degrees of activity but do not producethe high yields and antiknock p perties characteristic of the activecatalytic materials of the present invention. The active aluminas alsohave a tendency to catalyze the formation of abnormally largecarbonaceous deposits which is a factor avoided by the presentinvention.

Many clays such as kaolin and china clay which contain combined silicaand alumina in some naturally occurring condition have been described bysome as cracking catalysts and in some cases we have found that theygive mild catalytic efiects. These materials are considered, however, asbeing relatively inactive as compared with the precipitated hydratedsilicahydrated alumina, for example, employed in this invention sincethe commercial grade of kaolin employed in the specific examplessubsequently described has an activit corresponding to approximately A0of that of the active catalytic material of this invention on a weightbasis. These clays should not be confused with special clays of themontmorillonite type, particularly those which have been acid-treatedsince these acaaasv are of a higher degree of activity. A commercialgrade of the latter type of clay showed an activity corresponding toapproximately 40% of the active catalyst material of this invention on aweight basis. Clays of the latter type although having fair activityappear to be relatively unsuitable for mixing with the active catalystmaterials of this invention since mixtures thereof have not been foundto be highly stable when'in prolonged use at high temperatures. This isin distinct contrast to the mildly active clays above described.

The diluent materials employed in the present invention should benon-adsorptive or relatively non-adsorptive in order that they functionin the desired manner. It is believed that the carbon forming tendencyof a catalyst is in some degree dependent upon its adsorptive qualities.The carbon, so-called, which is a product of cracking is not in a truesense carbon but is hydrocarbonaceous and contains more or less highbolling hydrocarbons which are adsorbed on the catalyst. The catalyst ofthe present invention reduces the formation of some of this combustiblematerial by incorporating therein a relatively non-adsorptive diluent.

The relatively inactive materials above illustrated may thus bepractically non-porous, nonabsorptive, non-adsorptive and have nocatalytic activity or they may be somewhat porous and have a very mildcatalytic activity. These materials are not limited to relativelyinactive silica and/or alumina since other materials such as zircon orzirconium silicate, or magnesia may be used. It is necessary that thematerial 'be stable at high temperatures so that it does not sinter orflux and thereby reduce the structure and activity of the modifiedcatalyst. The material should therefore withstand prolonged treatment ata temperature of approximately 1600-1700 F. without any change. Anymaterial which will reduce at a temperature up to approximately 1100 F.or will be oxidized at approximately 1300-1500 F. cannot be employed.Materials which poison the catalyst or catalyze side reactions,ordeactivate the catalyst are also unsuitable. Thus, metals of group V111of-the periodic-table or their oxides should be absent or Present onlyin unavoidably small quantities otherwise they may become catalyticallyactive for the formation of carbon. Also, strongl basic materials mustbe absent since they apparently flux and deactivate the catalyst at hightemperature.

Referring now to the highly active catalytic materials, the mixture ofhydrated silica and hydrated metal oxide may be prepared by a number ofalternative methods which have certain necessary features in common aswill be subsequently described. Generally speaking, the catalyticmaterial resulting therefrom may be considered to comprise an intimateadmixture of silica and the metal oxide with the added relativelyinactive material in which all the individual components indicateactivity ranging from substantially no activity to a low activity ascompared to the high activity displayed by the aggregate. The activityis not an additive function and is relatively constant for a wide rangeof proportions of the acspect to'the active oxide components which oneis to be considered the promoter for the remaining gel componentaccordin to conventional terminology nor can it be definitely stated forexample how the silicon, aluminum, oxygen and relatively small amountsof hydrogen are chemically associated in the final catalyst composition.

The highly active material contained in the catalyst masses is thesilica-metal oxide cracking catalyst in which the hydrated silica formsthe primary or predominating material with which the remaining metaloxide components are intimately associated. The active catalyst materialis prepared in the hydrated gel condition by a number of alternativemethods and some of the methods which may be employed in mixing thehydrated silica and hydrated metal oxide components are as follows:

1. A precipitated hydrated silica gel may be suspended in a solution ofa salt of the metal for which a hydrated metal oxide is to beprecipitated in the presence of the suspended hydrated silica by theaddition of volatile basic precipitants such as ammonium hydroxide forexample r ammonium carbonate, ammonium hydrosulfide, ammonium sulfide orother volatile basic precipitants.

2. The precipitated hydrated silica gel may be mixed while in a wetcondition with a hydrated metal oxide prepared for example by theaddition ofv a volatile basic precipitant to a solution of a salt of thecorresponding metal.

3. The hydrated silica gel may be added to a solution of a metal saltand the hydrated oxide of the corresponding metal precipitated byhydrolysis, preferably by heating, or the hydrated silica gel may bemixed with a suitable amount of the metal salt and heated whereby themetal oxide will be deposited as a result of the decomposition of themetal salt. j

The character and efficiency of the ultimately prepared silica metaloxide catalytic material will vary more or less with the exactconditions of precipitation and/or mixing, the ratio of the componentsand added relatively inactive material and also with the purificationtreatment. The materials and the methods of preparation employed, andresulting catalytic material are not necessarily equivalent since theproper materials and methods may be so improperly used that the cost isgreatly increased and in some cases even unsuitable catalysts forprolonged use may be obtained.

One method of mixing alkali metal silicates and acid to form silica gelis to acidify an aqueous solution of sodium silicate by the addition ofan acid such as hydrochloric acid. The dilution of the alkali metalsilicate and the manner in which it is mixed with the acid influencesthe gelatinous nature of the hydrated silica gel which is formed. Whengradually adding the acid to a diluted alkali metal silicate,precipitation occurs for the major part in an alkaline solution and theprecipitate is generally of a gelatinous nature. The acid is added untilthe aqueous menstruum is highly acid whereupon the precipitation ofhydrated silica is practically complete. The excess acid may then beneutralized by the addition of ammonium hydroxide and in a preferredembodiment the hydrated silica is then purified according to thesubsequently described treatments.

An important feature resides in the fact that catalysts of greatlyincreased stability and efficiency in hydrocarbon cracking reactions areproduced when there is substantially complete exclusion of alkali metalions or impurities from the hydrated silica-hydrated metal oxidecomposites. At some stage in the preparation, the catalytic material isfreed from alkali metal impurities so that the catalyst composite willnot be subject to fluxing or slntering tendencies which may occur in theprolonged use thereof at high temperature if these impurities are notremoved. In one desirable procedure alkali metal ions are removed fromthe hydrated silica prior to mixing with the remaining hydrated metaloxides. The purification treatment may, however, be employed atsubsequent stages in the preparation and before or after mixing with therelatively inactive material m but generally to less advantage. Onemethod consists of washing the hydrated silica or the compositedhydrated silica-hydrated metal oxide mixture with acidic solutions toextract alkali metal impurities incorporated therein as in the formationof hydrated silica from alkali metal silicates.

Another method consists in treating with ammonium compounds or salts,such as ammonium chloride in solution or other halides, the sulfate, thenitrate or the acetate so that alkali metal ions will not besubstantially present after the washing treatment. According to anotherprocedure, salts of multivalent metals such as the salt of the metaloxide component may be used in removing the sodium or other alkali metalimpurities from the catalytic preparation.

As has been indicated above various methods may be employed in mixingthe hydrated silica component with the remaining hydrated metal oxidecomponent of the catalysts. One desirable a procedure consists insuspending the hydrated silica in a solution of a salt or salts of ametal or metals for which the corresponding hydrated oxides are to beprecipitated in the presence of the hydrated silica. Thus salts ofaluminum, zirconium, vanadium, magnesium, thorium and other desirablemetal salts may be used, and the hydroxides or hydrated oxides thereofprecipitated by the addition of a basic agent, preferably a volatilebasic precipitant such as ammonium hydroxide. According to this method apurified silica gel may be suspended in a solution of aluminum andzirconium chlorides for example, and hydrated alumina and hydratedzirconia precipitated by the addition of ammonium hydroxide. In thiscase, the hydrated alumina and hydrated zirconia are coprecipitated butgood results however may be obtained by depositing one of thesecomponents prior to the remaining component, or either one of thecomponents may be used and the other component omitted from thepreparation. The ratio of the components contributing to thecatalytically active portion of the catalyst preparation may be variedwithin relatively wide limits, the limiting factor being more inevidence with respect to small proportions than with larger proportionsof the various components. In general it appears that an approximationof the minimum proportions of the hydrated metal oxides to be employedrelative to the hydrated silica is of the order of 2 to 6 mol per cent.Smaller proportions may, however, be used and catalytic eil'ectsobtained. Relatively large percentages of the remaining hydrated oxidecomponents with respect to the hydrated silica component may be employedsuch as 50 by weight and higher in some cases. Generally speaking, theproportion of the hydrated oxides mixed with the hydrated silicacomponent are less than this amount in the preferred catalysts. Thecharreter and efiiciency of the ultimately prepared cat-- alyst willvary more or less with precipitation and/or mixing conditions, thepurification treatment, the ratio of the components, the amount andnature of the relatively inactive material mixed with the catalyticallyactive material, calcining conditions, etc. Several specific exampleswill be shown below to illustrate some of the preferred embodiments.

whatsoever the hydrated oxides used in the gel composite and theirmanner of preparation, they are mixed with the relatively inactivematerial above described prior to drying or forming into particles ashas been indicated above. The dry powdered materials may be mixed with alubricant and formed into shaped particles by briquetting orin pillingmachines. In subsequent calcination at high temperature of the order of100Q to 1500 F., the lubricant is removed by volatilizetion,decomposition and/or oxidation. As representative of the relativelyinactive materials which are added is a nearly white kaolin which ispractically free from impurities such as alkali or alkaline earth metaland iron compounds. In a preferred particle-forming procedure therelatively inactive material is added to the undried gel composite whichis then extruded. In fact one of the advantages of the present inventionresides in the fact that with the addition at the finely powderedmaterials described to the gel composite it is possibleto extrude themixture and obtain extruded particles of suitable strength and densityafter drying and calcining. These particles have better burningqualities during regeneration treatment than those 01' the gel whenextruded alone.

A desirable procedure of mixing the relatively inactive material withthe material consists in thoroughly mixing the gel with the powderedrelatively inactive material as in a ball mill or an intensive mixer.The suitability of the mixture for shaping into particles in theextrusion procedure and the strength of the particles resultingtherefrom varies with-the proportions of the gel and inactive powdermaterial employed in the mixture. Good results have been obtained fromthestandpoint of forming the particles and obtaining particles of goodstrength, stability'and activity when employing approximately 50% ofpowdered relatively inactive material and 50% of gelatinous catalyticmaterial on the dry weight basis. The proportions however may be variedover a relatively wide range depending upon the specific catalyst andthe operation in which it is to be employed. The moisture content andfineness of the powder can be regulated to mutually adjust variousproportions of the materials for the proper extrusion thereof. As aresult of adding the relatively inactive material to the highly activematerial there is reduced carbon formation upon the final catalystparticles when-in use in catalytic cracking reactions. The decrease inthe total carbon formation is proportionately greater than the decreasein the gasoline yield. The operation can therefore be readjusted toobtain more gasoline with the modified catalyst of the present inventionbefore it is necessary to interrupt the cracking reaction andperiodically regenerate the.

catalyst. Since the regeneration period of the part of the catalystbeing regenerated is nonproductive of gasoline, the decreased carbonformation upon the catalyst decreases the regeneration requirements. Theincrease in the mass of the contact material resulting from the additionthereto of the relatively inactive material further serves to reduce thetime of the regeneration treatment since the modified catalyst may, as aresult of its increased heat capacity, be more rapidly regeneratedwithout locally overheating the catalyst while also employing high roxygen concentrations in the regenerating gases.

catalytically active gel drocarbon oil processed.

The catalysts of our invention may be conveniently utilized in carryingout various types 01' hydrocarbon conversion reactions when employed asfilling material in tubes or disposed intrays or in chambers. Theaverage size of the. particles may vary within the approximate range or4 to 10 mesh more or less which is not restricted to any particularshape ormethod of particle formation. A hydrocarbon oil fraction isusually heated to substantially reaction temperature and the vaporsthereof are contacted with the catalyst particles. The hydrocarbonvapors may be passed downward through the catalyst and where large bedsof catalyst are involved, the passage of vapors may be restricted todefinite paths rather than allowing the vapors to have unrestrictedcontact with the large beds of catalytic material. Where this method isemployed, the temperature of the contact materials while in use orduring regeneration may be controlled by various operating procedures orby heat interchange devices. After the oil vapors have passed over thecatalyst as in catalytic cracking, the products may be separated intofractions unsuitable for further cracking and/or 'insufilcientlyconverted fractions which may be subjected to further crackingtreatment, and the gasoline and gaseous products. The higher boilingfractions may be removed from the system, may be reprocessed togetherwith the charging stock, or may be processed in separate passes so astoultimately obtain maximum utilization of the charging stock in producinggasoline products.

The catalysts may also be employed as a shaped or formed catalyst wherethe catalyst beds are moved in and out 01' contact with the oilprocessed, the catalyst being regenerated when out of contact with theoil. The catalysts may further be employed as a powder which is mixedwith the oil and the oil and catalyst mixture processed under crackingconditions.

Various types of hydrocarbon conversion reactions take place in thepresence of thecatalyst depending partly upon thetemperature, pressureand time conditions and partly upon the boiling point range and type ofhydrocarbons in the hy- These reactions may include carbon-to-carboncleavage, isomerization, cyclization, hydrogen transfer,dehydrogenation, hydrogenation and desulfurization reactions. In thecase of higher boiling hydrocarbons for example there is a cleavage oflong chained carbon-to-carbon bonds. Isomerization reactions may occurwhereby the lower boiling hydrocarbons formed tend to become more branchchained. Hydro-aromatic hydrocarbons present in the oil undergoingdecomposition or formed therein by cyclization of olefins may undergodehydrogenation to form aromatic hydrocarbons, and hydrogen from thesereactions may combine with other olefins present during reaction to formmore paraflinic hydrocarbons. The latter reactions tend to occur at thelower temperature given in the range of operating conditions whereasmore unsaturated hydrocarbons, particularly olefins are produced at thehigher temperatures employed. The hydrocarbons produced are generally ofa more branched chain structure than are those produced in thermalcracking treatment. The temperatures utilized may be a temperature fromabout 700 to about 1150 F. and the pressure employed may be from aboutatmospheric to about 500 or 1000 pounds per square inch. The spacevelocities employed may vary from approximately to 60, the spacevelocity being defined as the hourly volume of liquid hydrocarbonEXAMPIE I An active catalytic material was prepared according to theabove described procedures having a molar composition of100SiOzI2Al2OaZ4ZIO2. 64% by weight of this material was mixed with 36%by weight of an inactive silica which in this case was added to washedsilica hydrogel precipitated by the addition of hydrochloric acid to awater glass solution. After purifying the mixture by washing withacidulated water the mixture was disposed in a solution of aluminum andzirconium chloride and hydrated alumina and hydrated zirconiaprecipitated in the presence of the hydrated silica plus inactive silicamixture. The composited material was then washed, fil- -.tered and driedand the dried material formed a into particles of 6 to 10 mesh. Theseparticles were calcined at a temperature of approximately A Pennsylvaniagas oil was vaporized and the vapors thereof were contacted with the6-10 mesh particles of the above described preparation at a temperatureof 932 F. under atmospheric pressure for a' period of 6 hours using aliquid space velocity of 4. A similar run was made using thesilica-alumina-zirconia catalyst without added inactive silica. Theresults obtained in these runs were as follows:

Silica'almnina- Silica-alumina- Cam t zirconia without zirconia with Y5add inactive added inactive silica silica Gasoline yield, vol. per centof charge 27. 2 20. Octane Number 80 80 In this run there was a 4%decrease in gasoline yield when the inactive silica was admixed with thecatalytic material and the carbon deposit was decreased to the extent of38%.

when using zircon, zirconium silicate or zirconium spinel instead of theinactive silica, similar results were obtained.

EXAMPLEH Catalytic material of the molar composition 100SiOa:5AlzOa wasprepared according to the above procedure as follows: Hydrated silicawas precipitated by the addition of hydrochloric acid to a dilutesolution of a commercial water glass and the precipitated silica waspurifiedby washing with acldulated water until the hydrated silica waspractically free from sodium impurities. The purified hydrated silicawas then suspended in a solution of aluminum chloride and hydratedalumina precipitated in the presence of the suspended hydrated silica bythe addition of ammonium hydroxide. The silica-alumina composite wasthen washed and filtered and a portion thereof dried. Part of the driedmaterialwas pelleted with the aid of a lubricant to form y x 3 8"pellets, and part of the dried material was mixed with an equal weightof a commercial grade of powdered kaolin and also pilled with the aid ofa lubricant. The pelleted catalysts were calcined at a temperature ofapproximately 1500 F. Portions of the undried gel were mixed with thecommercial kaolin to produce mixtures which contained 50, '70 and ofkaolin mixed with 50, 30 and 10% of the silica-alumina gel on the drybasis. These mixtures were then extruded and carefully dried and thedried extrusions were calcined at a temperature of approximately 1500 F.These five catalyst preparations were used in the catalytic cracking ofa Mid-Continent gas oil having a 32.3 A. P. I. gravity and an initialboiling point of 464 F. in an Engler distillation, 50% distilling overthe 631 F. and 90% at 757 F. The cracking runs covered a period ofapproximately 30 days in which a cycle operation was used with one hourof contact with the hydrocarbon vapors alternating with one hour ofregeneration. The temperature of contact was approximately 965 F. andthe pressure was substantially atmospheric. A space velocity of four wasemployed and the regeneration with air was carried out at a temperatureof approximately 1300-1350 F. The results of these runs are given in thefollowing tabulation:

Active Catalytic Material, per cent 10 30 50 50 Relatively InactiveMaterial, per cent... 90 70 50 50 0 Shaping oiparticles by ExtrusionPelleting Gasoline yield, vol. per cent of charge:

15.5 21.2 24.9-27.0 28.4 14.7 20.4 24.8 23.9 28.4 Octane Number:

2.9 3.7 5.2 5.7 6.0 b) 3.6 4.0 5.1 5.8 7.2 Carbon Deposit, wt. per centof Charge:

0) .31 0.40 0.62 070 0.94 0.36 0.43 0.50 063 0.92 Carbon Deposit, wt.per cent of gasoline and gas yield:

41) Initial results.

0) Results alter approximately 30 days of use.

EXAMPLE III In the preparation of a catalyst composite of the typeindicated above, 450 volumes of 2.5 normal hydrochloric acid was addedslowly to 3400 volumes of a solution containing 415 parts by weight ofsodium silicate found by analysis to contain 29% silica and 8.9% sodiumoxide. The

mass of precipitated silica hydrogel was filtered,-

washed once and then added to a slurry consisting of parts by weight ofdiatomaceous earth in 2500 volumes of water. The mixture was stirred andfiltered and the filter cake was stirred into a slurry in-2500 volumesof water and then filtered, this operation being performed twice. Thefilter cake was next stirred into a slurry in 2500 volumes of water towhich 50 volumes of 0.1 normal hydrochloric acid was added and themixture was filtered. After this operation was performed twice thefilter cake was washed six times with 2500 volumes of water until thewash water was chloride-free and filtered. The filter cake was stirredinto a slurry in 3000 volumes. of water, mixed with an aqueous solutionconsisting of 40 parts by weight of aluminum chloride hexahydratedissolved in 500 volumes of water after which was added thereto 550volumes of aqueous ammonia solution containing 9 parts by weight ofammonia. The liquid wasr separated from the precipitate and admixeddiatomaceous earth by filtration and the filter cake was dried at 300 F.

- 11'' and then ground into a line powder, pressed into cake form,broken into 6-10 mesh particles, and calcined at 932 F.

Passage of Pennsylvania gas oil over the above described mass containingdiatomaceous earth, alumina, and silica at 932 F. during 6 hours using aliquid space velocity of 4 gave the results shown in Table 1, whichincludes comparative data on other runs made similarly in the presenceof a silica-alumina composite prepared in the same manner except withoutdiatomaceous earth and in the presence of another catalytic massprepared by precipitating alumina hydrogel in the same proportions onthe same sample of diatomaceous earth previously purified by washingwith acid and water.

TABLI 1 Cracking of Pennsylvania gas oilat 932 F. during 6-hour periodswith 4 liquid space velocity SiOriAhOs on Diatomaceon: Earth CatalystSiOQlAhO;

The above catalysts, after use, were reactivated by heating at 932 F. ina stream of air in order to burn off carbonaceous materials depositedduring the cracking runs. It was observed that thesilica-alumina-diatomaceous earth catalyst required only abouttwo-thirds as much air for reactivation as did thesiIica-aluminacatalyst.

This observation is evidence that less carbonaceous deposits accumulatedon the diluted catalyst during cracking.

A further advantage of the silica-aluminadiatomaceous earth composite asa cracking catalyst is its decreased cost over that of silicaaluminaalone. Thus as shown in Table 1 approximately the same yield of 80octane number gasoline and less carbon formed in the presence of adiluted catalyst as compared with silicaalumina catalyst.

The above results show in general that the catalyst or this invention isactive and stable. The data show that with a 50-50 mixture, i. 0., onepart of each, the relatively inactive and the active catalytic material,there is no appreciable 1 version conditions to amass? 12 reduction inoctane number initially or after extended use. Where possibly too muchmaterial is added as in the 10-90 mixture or the present I example, i.e., 1 part of active for 9 parts of relative inactive material there issome depreciation in octane number. The results also show that for aminor decrease in gasolineyield there has been a proportionately largerdecrease in carbon formation.

10 We claim as our invention:

1. A process for the conversion of hydrocarbon oil which comprisessubjecting the oil under conversion conditions to contact with acatalyst composite comprising precipitated hydrated u silica,precipitated hydrated alumina and precipitated hydrated zirconiasubstantially free of alkali metal compounds and tripoli substantiallytree of alkali and alkaline earth metal compounds and of metal oxideimpurities.

2 2. A process for the conversion of hydrocarbon oil which comprisessubjecting the oil under conversion conditions to contact with acatalyst composite comprising precipitated hydrated silica andprecipitated hydrated zirconia substaniially tree of alkali metalcompounds and tripoli substantially free of alkali and alkaline earthmetal compounds and of metal oxide impurities. 3. A process for theconversion of hydrocarbon oil which comprises subjecting the oil underconcontact with a catalyst composite comprising precipitated hydratedsilica and precipitated hydrated alumina substantially free oi alkalimetal compounds and tripoli substantially tree, 01 alkali and alkalineearth metal compounds and of metal oxide impurities.

JACOB E. AHLBERG.

L. THOMAS.

REFERENCES The following references are of record in the file of thispatent:

UNITED s'm'rns PATENTS Great Britain Jan. 23, 1935

